Manual Reference Pages - CONV (1)

CONTENTS

The response of a linear filter to an arbitiary input signal is the
convolution of the signal with the filters impulse response.
The impulse_response_file contains the impulse response which characterises the
filter, and the result of the convolution operation is the response of
that filter to the signal contained in the signal_file.

The signal_file must consist of binary 16-bit numbers (ie. shorts).
The impulse_response_file must consist of binary floats.
The output signal is the same length as the input signal and is written on
the stdout in binary 16-bit numbers.

If the signal_file consists of an impulse train, then the output should
be a repeated impulse response, ie. should be a repeated version of the
response_file.

The amount of the signal file to convolve in time units (s or ms) or in
samples (no units). Time units are converted to samples using the given
samplerate option. The string "max" is recognised as the remainder of
input.

2. domain

Select algorithm for convolution. In the time domain ("domain=time") the
discrete convolution formula is applied directly as a local averaging
operation on the input signal with weights obtained by time-reversing and
shifting the impulse response. The impulse response is assumed to be zero
for all time outside the given file. In the frequency domain
("domain=frequency") the FFT of the whole input signal is multiplied by a
frequency response function (the FFT of the impulse response), and
the result inverse FFTd.

Permission to use, copy, modify, and distribute this software without fee
is hereby granted for research purposes, provided that this copyright
notice appears in all copies and in all supporting documentation, and that
the software is not redistributed for any fee (except for a nominal
shipping charge). Anyone wanting to incorporate all or part of this
software in a commercial product must obtain a license from the Medical
Research Council.

The MRC makes no representations about the suitability of this
software for any purpose. It is provided "as is" without express or
implied warranty.

THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES
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SunOS 5.6

CONV (1)

1 September 1993

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